Method of fabricating contra-propellers



June 2, 1931. J. 1'. WISEMAN METHOD OF FABRICATING CONTRA-PROPELLERS 2 Sheets-Sheet 1 Filed Oct. 15, 1950 vm hl lNV-ENTOR WM BYMATTQRNEY g 9 June 2, 1931. .1. T. WISEMAN METHOD OF FABRICATING CONTRA-PROPELLERS 2 Sheets-Sheet 2 Filed Oct. 15, 1930 INVENTOR M J W- 8% ATTORNEY Patented June 2, 1931 UNITED STATES rsarn PATET FFICE JOHN T. WISE'MAN, OF BROOKLYN, NEW YORK, ASSIGNOR TO UNITED DRY DOCKS, IN-

CORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK 7 METHOD OF FABRICATING CONTRA-PROPELLERS Application filed October 15, 1930. Serial No. 488,760.

The present improvements relate, in general, to methods of shipbuilding and more particularly to an improved method of designing and constructing contra-propellers or rudders.

A primary object, of the improvements, among others, is to provide a novel method of fabricating contra-propellers whereby an increase in efliciency, saving in time and labor, and improvements in operation and function are derived. v

A further object is to provide an improved method of forming contra-propellers and mounting same in operative position.

provements will be apparent to those skilled in the art, upon reference to the accompanying specification and drawings, in which Fig. 1 is a front elevation of portions of a skeleton or dummy frame, merely portraying relative positions;

Fig. 2 is a side elevation of the elements illustrated in Fig. '1, showing .one step in the method;

Fig. 8 is a section on line 3 3 of Fig. 2, but illustrating a further step in the method;

Fig. 4 is a section of the finished contrapropeller associated with the rudder post of the ship, as though taken on lines aa of Fig. 2; 7

Fig. 5- isan outline representation in plan, of the completed contra-propeller; Fig. 6 is aside elevation of the ships stern with the completed article in position.

Referring to the drawings, illustrating one manner of practicing the method, a skeleton or dummy frame 10 is provided preferably with templets 11, 12 and 13. The element 11 may be a channel or beam to exactly represent the rudder post of the ship upon which the contra-propeller is to be mounted. Having set up the dummy rudder post 11 of the exact dimensions, pipes 12 and 13 are associated with the post in any desired manner. These elements are preferably, although not necessarily, tubular and are bent or formed into the desired shape for constituting the forward limits or ridge of the propeller. A series of diaphragms 14 to are fashioned to predetermine the outline of the contra-propeller. These element-s are pro-. vided with angles or flanges 21, and a cut out or recess 22, the latter substantially coinciding with the outline of the dummy post 11 so as to embrace it on three sides as seen in Fig. 3.

The diaphragms may now be welded in spaced relation to the pipes 12 and 18, so that they project in accurate alinement, with the dummy post 11 disposed in the several recesses 22 of the diaphragms, as illustrated in Fig. 2. The outside or cover plate 24; is

now riveted to the upstandingflanges 21 of. the diaphragms, but only on one side of the I Other objects and. advantages of the im-v contra-propeller. The fabrication of the propeller thus, far, may be observed in Fig. 3, where it is illustrated. about dummy post 11, one side being closed in by plate 24 and the other side remaining open, i. e., without any plate, for purposes of installation.

The remaining elements such as plates 26 and angles27 may be cut and fitted, so that the'units necessary for completion are all at hand for use in final assembly.

All of the foregoing operations may be accomplished in the shop or yard and in this semi-completed condition, the contra-propeller is removed from dummy post 11 and transferred to and mounted upon the rudder post 25 of the vessel in dry dock, about which it fits perfectly, due to the accurate sizeand alinement of recesses 22.

When disposed in the position i just described, the contra-propeller is'secured to the rudder post 25 by Welding the diaphragms thereto, this process being readily accomplished through the remaining open side of the device. Having now installed the propeller securely in place, the outer face plate 26 may be Welded to flanges 21 ofthe -diaphragms, and angles 27 riveted in position whereby a complete fluid tightenclosure is provided. A section of the finished article disposed about rudder post 25, riveted on one side and welded on the other is illustrated in Fig. 4. Figs. 5 and 6 depict the relation of the parts ofthe contra-propeller 9 in its association with the vessel.

Attention is invited to the fact, that certaingofthedi aphragms are provided with apertures 30, thereby affording communication therethrough to either side. Before the contra-propeller is sealed, any suitable liquid such as hydrolene is employed for filling the contra-propeller after it is in permanent po sition. s

Numerous advantages are derived in prac ticing the above described method. Heretofore, where it has been desired'to equip a Vessel with a device'of this character, the common practice has been to cast the contrapropeller and then mount it on the shipsrudder post. In vessels seeing service, it is necessary to dry dock them and then secure the cast propeller in place with the attendant confusion and delay in having numerous workmen about the same portion of the ship at the same time. Even when a fabricated propeller is employed and mounted element by element on the vessel, itis manifest that much time and labor are needlessly consume'di This practice has frequently required from 5 to 8 days, thus incurring considerable ex; pense as well as depriving the vessel of that period of usefulness; I

By'the present method, however, less than two days time is consumed,and to be exact, the vessel need be in dry dockfbut thirty hours, thereby permitting itto return to service promptly.

' In equipping a ship with this device, sub stantially fifty per cent. of the time and labor maybe accomplished in advance of the dry docking. The dimensions of the rudder post may be obtained in advance and in fact while the vessel is still in service, so that immediately the dry docking is accomplished, the half completed article may be mounted "on the rudder post and the completion of the fabrication and the permanent attachment effected. This practice obviously avoid'sconfusion and interference among shipfitters', welders, and riveters', all endeavoring to perform their tasks on the same article at the same time and in the necessarily small area where their work must be done. 7 7

Although the foregoing description' an'd illustrations have been devoted to the upper portion of the contra-propeller, it is understood that the lower portion thereof simi larly fabricated at the same time, the improved method being practiced in developing the entire article to its final and permanent form. p

Various modifications within the scope of the improvements may be apparent to those skilled in the art and may be practiced without departing from the scope and purview of the invention.

I claim:

1. The method of fabricating contra-propellers for vessels comprising. erecting a dummy rudder post, cutting the. propeller M parts to fit said post, securing certainparts to i one another on but one'side of the propeller While fitted about the post, transferring the resultant structure to the vessels-rudder post and securing the remaining parts to said structure and to the rudder post.

2. The method of fabricating contra-propellers for vessels comprising erecting a dummy rudder post, cutting the propeller partsto fit said post, securing interior parts to one anotherand plating one side of the propell'er while on said dummy post, transferrifig the resulting structure to' a vessels rudder post, securing said structure to said rudder post, and plating the remaining side of said propeller. 5

3. The method of fabricating contra-propellers for vessels comprising forming the propeller parts,- fitting, said parts about a dummy rudder post, securing certai nofsaid parts to one another while about said pastremoving the resulting structure andapply ing it onto a vessels fu'dderpost, securing said structure to said post and closing in the prop'eller and permanently'securing' it to said post. V

4. The method of fabricating contra-pro pellers for vessels comprisin'g ere'cting'a' forni, fitting brace members about said form, securing said members together in spaced relation while on said form, clcsing 'in one side of said brace members, removing the structure and applying itto apermanent rudder post,

securing same tosaid permanent post and closing in the remalnlng sides of said memhere to form a'liquid tight enclosure about saidpost. Q

5. The method of fabricating ta-tramspellers for vessels comprising erecting a dummy'ru'd'der pest-having the full size",

shape andproportions ofthe post to which the propeller is to be applied for actual use or service, cutting the propeller parts to fit said post, s'ecuringcertairi parts; to one" another on but one side'of the propeller while fitted one side of the propeller while fitted about the post, transferring the resultant structure to the vessels rudder post and securing the remaining parts to said structure and to the rudder post; i

7.The method of fabricating contra-propellers forvessels comprising first 'det'erinining the size andproportions of the rudder post to which the propelleristo be applied for actual service, erecting a dummy rudder post, cutting the propeller parts a at said post, securing certain parts to one another on ut one side of the propeller while fitted about the post, transferring the resultant structure to the vessels rudder post and securing the 7 remaining parts to said structure and to the rudder post.

8. The method of fabricating contra-propellers for Vessels comprising first determining the size and proportions of the rudder post to which the propeller is to be applied for actual service, its position with reference to the main propeller and the size and working characteristics of the said main propeller, erecting a dummy rudder post, cutting the propeller parts to fit said post, securing certain parts to one another on but one side of the propeller while fitted about the post, transferring the resultant structure to the vessels rudder post and securing the remaining parts to said structure and to the rudder post.

9. The method of fabricating contra=propellers for vessels comprising erecting a dummy rudder post OK the ship, cutting the propeller parts to fit said post, securing certain parts to one another on but one side of the propeller while fitted about the post, transferring the resultant structure to the vessels rudder post and securing the remainr ing parts to said structure and to the rudder post.

Witness my hand this 6th day of October, 1930, county of Kings, State of New York.

JOHN T. WISEMAN. 

